This invention relates to trailer and rigid body trucks and cargo containers, and more particularly to a body liner assembly for such trucks and containers.
Over the past decade, the transportation industry has gradually been converting their trailer and rigid body-type vehicles from the "exterior post" configuration to the streamlined "smooth-sided" configuration as offered by trailer and body manufacturers. This has been especially true since the energy crisis of 1973 focused increased emphasis and concern on energy conservation. Government, industry, and private sector testing has substantiated that smooth-sided vehicles increase fuel efficiency in highway or sustained speed operations in comparison with exterior post vehicles.
Tractor air deflectors and trailer (or body) aerodynamic nose mounted devices operate more efficiently with smooth-sided following vehicles as the increased air flow directed from the nose of the following vehicle can attach more readily to the trailer or body side. An additional benefit is obtained from the smooth-sided configuration in that the exterior surface is more suited for advertising and identification material than the discontinuous surface of the exterior post configurations.
Although the smooth-sided vehicle configuration has provided increased fuel efficiency, it has also heretofore created maintenance problems that have cancelled out any real dollar savings realized from the fuel efficiency. The maintenance problems have been especially prevalent with very large common carriers that operate many pieces of equipment on a round-the-clock basis. Specifically, the maintenance problems arise out of the configuration created when the posts are installed inside the vehicle and therefore present an irregular configuration in the vulnerable interior cargo space of the vehicle. If these posts are not covered with a smooth protective surface, they become prime targets for damage from forklifts utilized in the loading and unloading of freight. Damage to an interior post of a vehicle is both expensive and time consuming to repair.
Previously, the common practice was to span these posts with sheets of material by bolting or riveting the sheets to the post. Plywood of one-quarter inch thickness is believed to be the most common sheet material although metal is also utilized.
Commonly, the sheets are a standard four by eight foot size, the posts are normally two feet on centers, and the common practice is to rivet or bolt at one-foot intervals. Therefore, 27 rivets or bolts are used per sheet of liner.
Since plywood splinters and fractures easily, an additional liner is commonly fastened to the plywood at the lower portion of the trailer. This liner is usually a plastic material that affords a more slippery surface than the plywood. This plastic material is normally two feet in height and is installed fore-to-aft in the vehicle in a continuous length so as to avoid seams and joints that could be caught and torn by pallets, objects being loaded and unloaded, and the forklift itself. These bottom liners are fixed in the same manner as the plywood with rivets or bolts at one-foot intervals, both top and bottom. Thus, a 40-foot trailer would require 160 fasteners to install the bottom liner and would require 540 fasteners to install the plywood sheets for a total of 700 fasteners for a complete installation (which thus requires the drilling of 700 holes in the posts of the trailer). Thus, significant labor is expended in initial installation due to the use of these fasteners. Similarly, significant labor is required to replace damaged liners.
These numerous rivets or fasteners are susceptible to breakage or dislodging so as to extend outwardly in a protruding manner if the plywood sheets incur impact from a forklift or objects within the interior of the trailer. Impact forces on the sheets produce a "prying" reaction at the point of attachment to the post, i.e., the rivets or fasteners. This weakens, damages, or dislodges fasteners so as to cause the fasteners to protrude into the cargo space to catch on cargo and the forklift causing possible damage to the liner and posts. The dislodging of the fasteners can cause the plywood sheet and plastic liner to also protrude into the trailer body and subject them to inevitable damage. Thus, the dislodging of the fasteners or rivets produces a high risk maintenance condition.
Although the dislodging of the fasteners is a problem with both plywood and metal liners, the plywood liner also exhibits additional disadvantages. For example, the plywood is porous and even under the best manufacturing procedures tends to absorb moisture and gradually separate, splinter and fracture thereby requiring replacement. Additionally, the plastic bottom liner must be installed on the plywood in a continuous length to avoid seams and, therefore, if damage and replacement does occur, this liner must be replaced in total for the entire length of the vehicle. Because of its mass, plywood sheets inefficiently take up valuable cargo space and both plywood and metal are inefficient with respect to gross weight.